1. Field of the Invention
The present invention relates to an automatic seat belt system, and particularly to an automatic seat belt system having a mechanism of adjusting the height of a webbing worn by a seat occupant of a vehicle.
2. Description of the Related Art
In an automatic seat belt system of this type, one end of a webbing is anchored to a slider which is arranged to be capable of moving along a guide rail. The slider is linked to a motor through a flexible tape or a wire as an elongated member so as to be moved along the guide rail when the motor rotates.
Moreover, a slider retaining member (shoulder anchor) is arranged at the vehicle rearward side of the guide rail. The shoulder anchor is connected to a reinforcement member at the side wall of the vehicle body and is engaged with the slider so as to be above to retain it. The shoulder anchor is also arranged so as to be able to alter the connecting position with the reinforcement member along the guide rail.
When an occupant seats on a vehicle seat and closes a door of the vehicle, the motor is driven and the slider moves along the guide rail in the rearward direction of the vehicle. The slider then abuts against the shoulder anchor and is retained thereby, causing the webbing to be applied to the occupant.
By changing the connecting position of the shoulder anchor by manual operation, the occupant can also adjust the retaining position of the slider, i.e., the height of the webbing worn by the occupant, enabling even an occupant with a different type of physical build to obtain an optimum webbing fastened state.
In such an automatic seat belt device having the prior art webbing fastening height adjustment mechanism, however, the slider retained by the shoulder anchor is linked to the motor through the flexible tape or the wire cable as described above, so that the motor also rotates through the flexible tape or the wire cable when the occupant moves the shoulder anchor together with the slider along the guide rail in order to adjust the height of the webbing worn. A large operating physical force is required for that, hence causing a defect that the height of the webbing worn cannot be adjusted readily. Especially when a reduction gear adapted to the motor is one having a structure not to be able to reverse the rotation, the shoulder anchor may not be moved causing the webbing fastening height not be able to be adjusted.